The following data present the gross income of a given category of family compared with the Retail Price Index over a seven year period:
Year: 1998 1999 2000 2003 2004 2005 2006
Family
Income
(N'000s): 10000 12105 12809 13600 13911 14001 14500
Retail
Price
Index: 134.8 157.1 182.0 197.1 223.5 263.7 295.0
(a) Compute the indices of real gross income (1998 = 100)
(b) Compute the indices of real gross income using the Retail Price Index as indicator.